1. Field of the Invention
The present invention relates to a head-up display device.
2. Description of the Related Art
A head-up display device causes a driver to view projection light by reflecting projection light emitted from a projection light emitting unit by a reflecting member and projecting the projection light reflected by the reflecting member onto a window, for example, a windshield. The projection light is corresponding to various pieces of information such as a vehicle traveling state and an amount of the information thereof has been increasing in recent years.
The head-up display device preferably sets a position on the windshield onto which the projection light is projected, that is, a position on the windshield on which the information is displayed to a position in accordance with a height of a sight line of the driver because the height of the sight line differs depending on drivers in seated states. In view of this, a head-up display device having a configuration in which a reflecting member is supported rotatably on a housing of the head-up display device and a rotation position thereof is held has been proposed.
For example, Japanese Patent Application Laid-open No. 2005-186913 discloses such a conventional technique.
The housing of the head-up display device is fixed to a vehicle with a movable portion interposed therebetween because the reflecting member is rotatable. Looseness and allowance exist in the movable portion (for example, a portion between a rotating shaft and a bearing and a driving force transmitting mechanism of a rotating mechanism by which rotating force for rotating the reflecting member about the rotating shaft is transmitted to the reflecting member). The reflecting member does not vibrate in synchronization with vibration of the vehicle due to the looseness and allowance.
Accordingly, when the driver the sight line of which sways in synchronization with the vibration of the vehicle views information displayed on the windshield, the information seems to sway because the reflecting member vibrates in a manner different from a vibration manner of the vehicle. Visibility significantly lowers when the amount of the information that the head-up display device displays on the windshield is increased.